"The negotiations on Turkish Stream have been suspended,” said Novak. The pipeline was discussed in the framework of the Russian-Turkish Intergovernmental Commission on Trade and Economic Cooperation, which has been suspended, he added.

Gazprom's project has been on hold since the jet incident, awaiting instructions from the Russian government.

“We're expecting the head of state, in all likelihood, could declare the freezing of Turkish Stream, or at least some kind of timeout could be announced," an anonymous Gazprom source told Reuters on Wednesday.

“We are still hoping that Turkish Stream will be pushed back by a few years, rather than completely canceled," a second source said.

The Turkish Stream gas pipeline is one of the major projects for Russia and Turkey. It aims to deliver Russian natural gas to Turkey via the Black Sea, and then further to Southern Europe. The start of construction was scheduled for June but has been delayed as Moscow and Ankara failed to reach an intergovernmental agreement.

Since the incident with the Russian warplane, the future of the project has been unclear. Russian Economy Minister Alexei Ulyukayev assumed last month that Turkish Stream and the Akkuyu nuclear power station could be among the projects affected by sanctions against Turkey.

However, neither Turkish Stream, nor Akkuyu were included in the list of economic sanctions against Turkey ratified by the Russian government on Tuesday. The list included an embargo on food products and a ban on charter flights.

Problems with the Turkish Stream project have not affected the delivery of Russian gas to Turkey via the existing Blue Stream pipeline.